"Pete Bertini" wrote in
news
....
So, I would have balanced open-wire feedline from the dipole to
the 4:1 balun followed by a 1:1 common-mode RF choke with

I should have mentioned that 4:1 baluns integrated into ATUs are most often
voltage baluns.

When operated near a voltage maximum with high standing waves, they can be
very lossy. Sometimes it is claimed that they 'tame' difficult antennas
better than current baluns, which is often due to their internal loss. The
problem as such is not the balun, it is the extreme load presented by a
very poor antenna, and the lossy balun is a poor (grossly inefficient)
circumvention.

So, when a 4:1 voltage balun allows a match where a 1:1 current balun
doesn't, the problem is probably the antenna, not the balun.

Owen